Rework app bar, notes layout, Settings/Admin/login restyle

App bar: brand, Studies / Read Bible / Reading Plans, and one account menu
(theme, Settings, Admin, Log out). Study stage: notes get their own box above
the resources in the right column. Settings, Admin and the login page use the
reader themes; add a theme-aware danger colour.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/pages/ExportPage.jsx

@@ -47,7 +47,7 @@ export default function ExportPage() {
                   className="min-w-0 flex-1 truncate rounded-lg border border-[var(--r-line)] bg-[var(--r-bg)] px-3 py-2 text-xs text-[var(--r-sub)]" />
                 <button type="button" onClick={share.copy} className="shrink-0 rounded-lg bg-[var(--r-accent)] px-4 py-2 text-xs font-medium text-[var(--r-on)]">{share.shareCopied ? 'Copied!' : 'Copy'}</button>
               </div>
-              <button type="button" onClick={share.revoke} disabled={share.shareBusy} className="text-xs text-red-700 hover:underline">{share.shareBusy ? 'Revoking…' : 'Revoke link'}</button>
+              <button type="button" onClick={share.revoke} disabled={share.shareBusy} className="text-xs text-[var(--r-danger,#b42318)] hover:underline">{share.shareBusy ? 'Revoking…' : 'Revoke link'}</button>
             </div>
           ) : (
             <button type="button" onClick={share.enable} disabled={share.shareBusy} className={btn}>{share.shareBusy ? 'Enabling…' : 'Enable sharing'}</button>